Guides / Vedic and Western astrology
Sidereal vs tropical astrology
Tropical astrology follows the seasons. Sidereal astrology follows the stars. They share the same planets and differ in where 0° Aries is placed.
Two frames for the same sky
The planets are where they are. Astrology then names their positions against a zodiac. Tropical astrology sets 0° Aries at the March equinox, so the signs stay aligned with the seasons. Sidereal astrology sets the signs against the constellations, so the frame slowly slips relative to the equinoxes.
Neither frame is a modern invention. Hellenistic astrology used a tropical reference. Indian astrology developed a sidereal practice and, in the last century, standardized the Lahiri ayanamsha for converting between the two.
How to use both on Inner Light
The birth chart page calculates both. The Vedic tab shows sidereal positions and a D1 Kundli. The Western tab shows tropical positions and a natal wheel. Switch between them from the same birth details. The underlying ephemeris does not change; only the zodiac frame does.
Common questions
- Why is my Vedic Sun often the previous sign?
- The sidereal zodiac currently sits roughly 24 degrees behind the tropical one. A tropical planet in the early degrees of a sign often falls in the previous sign when measured sidereally.